In the previous post, we mentioned that data is everywhere. But where does it actually live?
Every company or organization you can think of relies on some form of database to store information.
What are databases?
Databases store, organize, and provide an easy way to access data.
A database contains related data in an electronic format. The most common type is the relational database. In a relational database, data is stored in tables with rows (records) and columns (fields).
A record contains specific data, such as information about a particular customer or product. A field contains data about one aspect of the table's subject, such as a first name or product price.
The most efficient and flexible way to access structured data is through the relational database model.
A relational database can contain several tables. The different tables are connected by one or more common fields called keys. Key fields that connect tables may appear with different names in different tables, but they refer to the same piece of information.
There is a visual representation of a database called a schema. The schema diagram describes how a database is organized and includes:
The number and names of tables in the database
Fields in each table
Keys connecting the tables
Databases can contain large amounts of data, but most of the time, you won’t want to view everything at once. In most situations, you’ll only want to see a selection of data that meets certain criteria.
Retrieving data from a database is known as querying.
Example of a query: The number of individuals in a database who live in a given city.
A database is useless if you can’t extract meaningful information from it. Query languages allow you to retrieve information from a database using computer programs.
SQL stands for Structured Query Language and allows you to query relational databases containing structured data. SQL is a standardized database query language.
SQL is a key skill across every area of the data industry. Even if you need to work with unstructured data or non-relational databases, knowing even a bit of SQL gives you a competitive advantage. More modern and complex database technologies like NoSQL (Not Only SQL) build on it.
You may have used spreadsheets like Excel to work with data before. How do they relate to databases? Databases are better suited for storing larger and more complex collections of data. Spreadsheets are useful for quick visualizations and summaries.
Use a spreadsheet when working with a single table.
Use a database when dealing with complex relationships between data types.
Cheers, Irina 😊